1. Field of the Invention
The present disclosed technology relates generally to suspension systems, and in particular an air spring down-pressure system for an agricultural implement.
2. Description of the Related Art
Agricultural implements that work the soil require mechanical force to penetrate down into the soil and move forward through the soil. Typically, penetrating force, also referred to as down pressure, is generated by the weight of the implement and mechanical force created by a suspension system using helical or leaf springs.
Grain drills, also referred to as openers, are agricultural tilling implements that allow farmers to quickly and efficiently plant row crops using agricultural machinery. Openers are independent units attached to a structure, such as a tool bar, which is pulled behind a tractor. Multiple openers are usually attached to a tool bar and spaced apart at specific intervals. As the opener moves forward, it plants seeds in the soil by penetrating and separating the soil with a pair of overlapping discs to create a trench in which a seed is deposited. Additional furrow-closing components flank the discs and trail behind them for returning the soil to the open furrow or trench and for covering the deposited seeds.
The depth of the trench created by the discs depends upon the condition of the soil, the amount of residue present, the opener and the amount of down pressure exerted by the opener against the ground. Down pressure is created using a suspension system that generates mechanical force to bias the opener discs down. Conventional openers typically have suspension systems with springs for exerting down pressure. However, due to the spring constant factors associated with mechanical springs, down pressure from spring action varies over the range-of-travel, with greater forces being exerted at full compression/extension conditions. Moreover, the mechanical linkages and pivot points associated with springs tend to increase problems associated with operating and maintaining such spring-based conventional implement suspension systems, still further, because of the mechanical geometries of spring-based suspension systems, they are vulnerable to contamination from soil and residue displaced during the planting process. Other disadvantages include lack of adjustability and frequency of repairs and maintenance.
What is needed is a suspension system with fewer moving parts and pivot points than conventional systems, which has fewer wear points, which provides more consistent down pressure throughout its vertical travel, and which permits infinite down pressure adjustment from a single control point. Heretofore there has not been available a suspension system with the advantages and features of the disclosed subject matter.